Visible light induced photocatalytic inactivation of bacteria by modified titanium dioxide films on organic polymers

Commercially available polypropylene foil was pretreated with a low temperature oxygen plasma and covered with a thin fi lm of nanocrystalline titanium dioxide by dip coating. The fi lms were then photos- ensitized by titanium( IV ) surface charge transfer complexes formed by impregnation with catechol. The photoactivity of the coatings up to 460 nm was con fi rmed by photoelectrochemical measurements. The photoinactivation of Escherichia coli and Staphylococcus aureus was evaluated by a glass adhesion test based on ISO 27447:2009(E) in the presence of visible light. The coating showed good antimicrobial activity induced by light from a light-emitting diode (405 nm), in particular towards E. coli ATCC 25922 strain. Adaptation of ISO 27447:2009(E) to assess bacterial photoinactivation by photocatalytic coatings will allow this procedure to be applied for the comparison of photoactivity under a range of irradiation conditions

The application of genetics methods to differentiation of three Lactobacillus species of human origin

In recent decades, the interest in probiotics as diet supplements or drugs has increased. In order to determine a specific bacterial isolate to be probiotic, it is necessary to describe precisely its probiotic characteristics and taxonomic properties, including the strain level. Most of the well-known genotyping methods were designed for the commonly-found pathogenic bacteria. The objective of this study is to undertake an attempt at standardization of FISH, RAPD and PFGE methods to genotype and identify the bacteria belonging to Lactobacillus fermentum, L. gasseri and L. plantarum species. The FISH probes have been designed and tested for Lactobacillus fermentum, L. gasseri and L. plantarum species and an endeavor has been made at standardization of RAPD and PFGE methods for these bacterial species. Moreover, the MLST method was applied to differentiate Lactobacillus plantarum strains. L. plantarum isolated from humans could not be genetically diversified with the use of RAPD, PFGE or MLST methods; only the strains originating from plants have displayed diversification among themselves and have been different from the strains of human origin

Effect of hydrogen peroxide of bacterial origin on apoptosis and necrosis of gut mucosa epithelial cells as a possible pathomechanism of inflammatory bowel disease and cancer

A series of in vitro experiments was arranged to assess effects of different concentrations of H2O2 contained in bacterial cultures on apoptosis and necrosis of HT-29 line cells representing human gut epithelium. On the basis of cytofluorimetric assays it was possible to demonstrate that supernatant of the Lactobacillus strain producing hydrogen peroxide (L. delbrueckii CU/22) was able to induce both apoptosis and necrosis in human epithelial culture cells HT-29. Both effects were more prominent than those visible under influence of supernatant of the non-H2O2-producing Lactobacillus strain or chemically pure H2O2 at the same concentration used as a control. In the light of this study and also other reports on damaging effects of hydrogen peroxide and superoxide radicals of bacterial origin on colonic cells, commensal bacteria of the human gut producing H2O2 may be involved in pathomechanisms of IBD by perpetuating the inflammatory reaction and increasing apoptosis and necrosis. There is a promise that probiotic preparations containing Lactobacillus bacteria will be successful as adjunct therapy of IBD and it is, therefore, postulated to make a very careful selection of the Lactobacillus strains as candidates for probiotics indicated to ameliorate the course of IBD, before starting clinical trials

Possible role of Escherichia coli in propagation and perpetuation of chronic inflammation in ulcerative colitis

BACKGROUND: This study investigated a possible role of Escherichia coli in propagation and perpetuation of the chronic inflammation in ulcerative colitis (UC). The lesions of UC are located superficially on the rectal and/or colonic mucosa. It is suggested that the commensal bacteria of the digestive tract may play a role in the pathogenesis of UC. Several studies have demonstrated proliferation of E. coli in the gut of UC patients. An increase in the number of E. coli in the inflamed tissue is most probably related to the abundance of iron ions produced by the bacteria. METHODS: Colon mucosal biopsies were collected from 30 patients with acute-phase UC, both from tissues with inflammatory changes (n = 30) and unchanged tissue with no inflammatory changes (n = 30) from the same patient. Biopsies were also taken from 16 patients with irritable bowel syndrome diarrhea who comprised the control group. Quantitative and qualitative analysis of the biopsy specimens was performed using culture methods and real-time polymerase chain reaction (PCR). Genotyping of the E. coli isolates was done using pulsed-field gel electrophoresis. Multiplex PCR was used to compare the E. coli strains for the presence of genes responsible for synthesis of iron acquisition proteins: iroN, iutA, iha, ireA, chuA, and hlyA. RESULTS: We demonstrated that there was a significant increase in the number of E. coli at the sites of inflammation in patients with UC compared to the control group (P = 0.031). Comparative analysis of the restriction patterns of E. coli isolated from inflammatory and unchanged tissues showed that the local inflammatory changes did not promote specific E. coli strains. There was a significant difference in the frequency of the iroN gene in E. coli isolated from patients with UC as compared to the control group. CONCLUSIONS: The increase in the numbers of E. coli in the inflammatory tissues is related to the presence of chuA and iutA genes, which facilitate iron acquisition during chronic intestinal inflammatory processes

The dual role of Escherichia coli in the course of ulcerative colitis

BACKGROUND: This study examines the dual role of Escherichia coli in the course of ulcerative colitis (UC). The intestinal microbiota is considered to play an important role in UC pathogenesis, but how E. coli contributes to inflammation in UC is still unknown. On the one hand, we demonstrated that there was a significant increase in the number of E. coli at the sites of inflammation in patients with UC, which can lead to immune system activation, whilst, on the other hand, E. coli may contribute to the resolution of inflammatory reactions since E. coli can inhibit hydroxyl radical formation by eliminating substrates of the Fenton reaction, by assimilating ferrous iron (Fe(2+)) and inducing the decomposition of hydrogen peroxide (H(2)O(2)). On this way, E. coli may affect the initiation and/or prolongation of remission stages of UC. METHODS: Ten E. coli strains were isolated from the colonic mucosa of patients in the acute phase of UC. Using PCR, we examined the presence of genes encoding catalases (katG and katE) and proteins participating in iron acquisition (feoB, fepA, fhuA, fecA, iroN, fyuA, and iutA) in these E. coli strains. To determine if iron ions influence the growth rate of E. coli and its ability to decompose H(2)O(2), we grew E. coli in defined culture media without iron (M9(-)) or with ferrous ions (M9(Fe(2+))). Expression levels of genes encoding catalases were examined by real-time PCR. RESULTS: All investigated E. coli strains had catalase genes (katG, katE), genes coding for receptors for Fe(2+) (feoB) and at least one of the genes responsible for iron acquisition related to siderophores (fepA, fhuA, fecA, iroN, fyuA, iutA). E. coli cultured in M9(Fe(2+)) grew faster than E. coli in M9(-). The presence of Fe(2+) in the media contributed to the increased rate of H(2)O(2) decomposition by E. coli and induced katG gene expression. CONCLUSIONS: E. coli eliminates substrates of the Fenton reaction by assimilating Fe(2+) and biosynthesizing enzymes that catalyze H(2)O(2) decomposition. Thus, E. coli can inhibit hydroxyl radical formation, and affects the initiation and/or prolongation of remission stages of UC

A role of hydrogen peroxide producing commensal bacteria present in colon of adolescents with inflammatory bowel disease in perpetuation of the inflammatory process

Bacteria in the gut play a central role in the initiation and progress of inflammatory bowel disease (IBD). This study was prepared to elucidate the role in the inflammatory process of the bacterial species which are able to produce hydrogen peroxide, present in samples taken from colon lesions in adolescents with inflammatory bowel disease. Fifty eight adolescents were enrolled into the study from January 2004 to October 2006 in Cracow, Poland. Biopsies and stool samples were collected. Bacteriological examinations and measurements of hydrogen peroxide production by enterococci, streptococci and lactobacilli were performed. For the first time it has been shown here that HP producing bacteria may contribute to increased amounts of hydrogen peroxide in the inflamed mucosa of Crohn’s disease and ulcerative colitis patients. Moreover, we have been able to demonstrate an increase of total populations of aerobic bacteria but not anaerobes in the studied samples of mucosa of adolescents with inflammatory bowel disease which is an indirect evidence of higher oxygen tension present in inflamed tissues in IBD. We have also been able to demonstrate the direct relationship between presence of blood in stools of IBD adolescents and increased populations of Enterobacteriaceae but not streptococci in samples of colon mucosa. It is, therefore, possible that different products of Enterobacteriaceae and especially their lipopolysaccharides may also contribute to perpetuation of the chronic colon inflammation

Lactoferrin metal saturation : which form is the best for neonatal nutrition?

We evaluated the impact of metal saturation of lactoferrin (with iron and manganese) on population numbers of pathogenic species relevant for neonatal sepsis that commonly originates from the gut due to bacterial translocation. Little attention has been paid to how metal ions bound to the protein affect its activity. Several reference and clinical strains as well as probiotic strains were incubated with different forms of lactoferrin: metal-depleted (apolactoferrin), iron-saturated (hololactoferrin) and manganese-saturated lactoferrin. We also attempted to confirm the observed effects of lactoferrin forms in vivo using rat pups. The observed decrease in population numbers of Gram-negative rods could not be confirmed by quantitative plating—lactoferrin may regulate these populations diversely (e.g., by anti-biofilm activity) and contribute to the inhibition of inflammatory response. We did not see any effect of lactoferrin forms on staphylococci and bifidobacteria. However, we have noted a significant increase of population numbers of Lactobacillus strains upon incubation with manganese-saturated lactoferrin. These results were confirmed in vivo in a rat model. Metal saturation is an underestimated factor regulating lactoferrin activity. Some forms are more potent in the inhibition of pathogenic species while others, such as manganese-saturated lactoferrin, could contribute to the restoration of gut homeostasis